Metal prep tips and tricks and fails

Okay, metal prep for next step after cut…like it or not it needs to be done

I did the muiratic acid thing a couple times , worked great.

Pros
It pickled HRS and got a nice CF look with no dross

Cons
Expensive
Evaporated very fast (see #1)
Toxic fumes
Rust if not quick enough with water rinse and dry
Will rust any carbon steel in vapor path.

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Simple grinding disk/flap wheel etc

Pros

Can give unique patterns in metal, that are later high lighted with finish.
Easy and fairly cheap

Cons

Dirty nasty and grind dust destroys surfaces, bearings, guides and electric motors near by.
Eye, nose and ear protection needed


Vinegar
Never used it but plan to tonight. After hearing folks talk about soaking overnight
Pros?

Cons?

We
Shall see…4 gallons with tax was $11.55 5%acidity

Add anything to this

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I have used vinegar. I let it soak all day while I was up skiing and came down and cleaned it up.

Pros
Easy and fairly cheap

Cons
Similar to muriatic acid you need to get it cleaned up and rinsed off or it will promote rust.

General observations:
You need a bath large enough to immerse the part for several hours. In my case I was doing (2) 36"x48" signs. I made a bath out of old 2x4s and plywood and lined it with plastic.

When I did it it was cold and rising it off outside was a little painful.

I used i wire brush during the rinsing process to remove the mill scale and a 3M abrasive scotch-brite bristle disk with my battery powered angle grinder to do the final cleaning(per NTD racing on youtube). It worked well and was much easier than the flap disc method. Again the key is thoroughly rinsing them off quickly after removing them from the vinegar bath.

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I’ve used vinegar long enough to figure out how long it lasts. It lasts about 6 months if you use it a lot.

I have it in a large shallow (under bed storage) container with a lid. I soak parts overnight and the scale rinses off with the hose. It leaves a finish similar to sandblast.

I found out that it does stop working after a while. The last few pieces I put in there still had the mill scale firmly attached after several days of soaking. I put them in a small container of fresh vinegar and they were clean in about 4 hours.

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I use vinegar with plastic pools. Even a couple hours with fresh vinegar enough. Then rinse in baking soda water slows rusting. Sandblast then paint or powder coat

Well, went to 10 dollar stores yesterday looking for a plastic pool, they only had 3ft ones. So wife said use the old purple sled :+1: went to the building, but it is only 16in wide…wop,wop…wop.

So used a smaler container i had and did other parts in vinegar, just checked them after about 16hrs…they need more, will check at lunch.

Definitely not as fast as muiratic acid…

I use vinegar successfully you just cant be in a rush. Here is a piece I left in for a week. That’s overkill but I was out of town. It was cut out of the sheet it is sitting on.

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Wow that’s a long time. Most I have ever waited is 8 hours. I do lightly brush it with a wire brush as I rinse it off.

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If you leave in vinegar for a couple of days the mill scale will rinse right off. I picked up a Bauer Surface Conditioning Tool from Harbor Freight and the 40 grit wheel is a beast. It will remove anything you throw at it. I removed two coats of powder coat from a couple of pieces like it was an eraser.

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Home Depot sells a 30% vinegar for $20 a gallon. Its pricey compared to the 5% stuff from the grocery store, but it works much faster. I mixed a few gallons in with my 5% stuff to bring it up to about 10%.

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Amazon has 45% vinegar for $20 per gallon. That’s what I have been using for small parts.

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Ya wasn’t really intentional as I said I was out of town but the results are good! Nothing other than rinsing on that piece…

I’ve been using apple vinegar - $5 for 2-gallon jugs at the grocery store. I don’t do big parts, but it works great. I have a small plastic storage bin - 12"X6"X4" deep pour in about a quart and let set - usually over night, flip and second side in less than 3-hours.

Life has been hectic/pain in the butt this week and parts have been in vinegar since i got it, walked by them last night and it looked like a frothy black and rusty alien blob, will pull out tonight and see damage :grimacing:

ETA…not happening tonight…here is alien blob

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It’ll be fine. You can wipe or rinse it off and you’ll be down to clean steel.

I recommend a good rinse with the hose, then wipe dry. That really minimizes the flash rust.

Best thing I found for plastic container is a dog crate tray.
Dog crate tray

I also lay some of these plastic rods under the piece to allow the backside to clean better.
Plastic rods

A little agitation with a brush like this helps to.
cleaning brush.

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When i was working in california, we used Metal Descaler/Degreaser from IMS (Industrial metal supply). I am still trying to figure out what it was made of. They wont ship it unless you live in california or arizona for some reason. Basically we put it in a plastic spray bottle and then just a couple of sprays on stock metal, wait 10-30 seconds and then wipe off. it would take mil scale, grease, and light rust off. Does anyone else know what this is?

Sounds like Iron Phosphate.

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I think you might be right, what i’m reading about iron phosphate sounds very similar to what i was using.

Especially the part about turning the rust spots black. Thank you for the lead. I’m gonna find something now

I get it from Columbia Coatings and mix it 20 to 1 with water in a spray bottle. It will eat up the metal rod in a pump up spray bottle…

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